Re: [math-fun] notation query

In my undergraduate topology class, an overbar was commonly used for the closure of a set. Since we're not talking about the complex numbers, the most obvious closure adds +oo and -oo. But yes, they should have said this. At 11:09 AM 9/22/2013, James Cloos wrote:

I read a paper today which used a notation I do not remember seeing before; I'm curious whether it is common. The paper discussed the union of the reals with a pair of points at infinity by using an overbar over the set R.